Thank you very much for the useful information.
This is called Leucopenia (low white cell count) and there are many reasons for this.
Bone marrow disorders
B-12 and folate deficiency
And many others.
4.3 is not considered seriously low or too low.
This is mild.
And in your case the most likely possibility is of a viral infection, which classically gives you fatigue, lethargy as well as mild derangement in the laboratory tests like leucopenia (low white cell count) and raised ALT (liver test).
This is in general a transient state and reverse back to normal in few days or a week.
At this point, i will suggest you to have rest.
Keep yourself adequately hydrated.
Well balanced diet.
And Co-enzyme Q-10 supplements will also help.
Get the test repeated after a week and see if this reverse back to normal or not.
If the symptoms persist, and the lab results do not improve or get worse after a week or so, have this discussed in detail by your doctor in order to chalk out further management plan and tests that suit best to your needs.
But honestly, i personally feel (as per my experience) that it is transient and will improve spontaneously.
I hope this clarifies and answers your question.
I would have been worried too if I were at your place, but let me reassure you that this is a treatable condition and carries a good prognosis with appropriate management.
It was a pleasure assisting you and thank you very much for visiting us.
My goal is to provide you with Excellent Service - if satisfied with the response, Please do not forget to Rate my service.
If you feel you have gotten anything less, please reply back, I am happy to address follow-up questions.